You can report a cyber crime and criminal activity to authorities via the phone or online depending on your country. If unsure, contact your local police station to file a complaint.
Report a cyber crime for: child pornography or exploitation, computer intrusion (hacking), Internet fraud and spam.
USA: File a complaint with the Federal Bureau of Investigation Internet Crime Complain Center (IC3)
The United States Department of Justice
The primary federal law enforcement agencies that investigate domestic crime on the Internet include: the Federal Bureau of Investigation (FBI), the United States Secret Service, the United States Immigration and Customs Enforcement (ICE) , the United States Postal Inspection Service, and the Bureau of Alcohol, Tobacco and Firearms (ATF) . Each of these agencies has offices conveniently located in every state to which crimes may be reported. Contact information regarding these local offices may be found in local telephone directories. In general, federal crime may be reported to the local office of an appropriate law enforcement agency by a telephone call and by requesting the “Duty Complaint Agent.
EUROPE: European Cybercrime Centre for Reporting Cybercrime
In all countries, if you feel your life is being threatened contact local police immediately.